Coming into camp, perhaps the biggest question mark was who was going to be the Mets everyday second baseman.  There is no shortage of candidates.  At last count, there was Castillo, Murphy, Emaus, Turner, and possibly even Tejada (and don’t forget that Hu and even Willie Harris in a pinch can also play second).  And of course, there are various permutations with platoons and minor league options and so forth.I’ve often wondered how teams make sensible evaluations during spring training “battles.”  From a young age, fans learn that Spring Training stats don’t matter.  Further, how much can really be gleaned from watching players in drills?  In reality, what must go on is that teams go into the Spring with a set of notions as to what they’d like to see and then find evidence from the assorted Spring activities to confirm those notions.Let’s take a look at what baseball prospectus has to say about the various choices using my favorite overall offensive comparison tool, TAv (which as a reminder is a measure of total offensive value that incorporates baserunning and where overall league average is .260).  The TAv’s are 2011 projections:Murphy--.267Emaus—.259Castillo--.241Turner--.252Tejada--.216On projected offense alone, Murphy gets the job.  Of course, this is not a tryout for designated hitter and the gap between Murph and Emaus offensively isn’t that great.  It’s possible Emaus’ defense makes him the overall better choice.  And, Murphy could make the Mets as a utility guy or even get optioned to Triple-A.  In contrast, Emaus has to be offered back to the Blue Jays if he doesn’t make the team.But wait, Emaus bats right-handed and Murphy left.  So platoon them!  There’s certainly some support for doing so.  Murphy’s line against righties in 2009:  .275/.324/.430.  In triple-A, last year Emaus actually struggled against lefties, hitting only .206/.333/.365, but those numbers may be anomalous because he actually crushed lefties in winter ball to a .448/.515/.690 tune.However, things aren’t quite that simple.  For one thing, if the Mets platoon Emaus and Murphy at second, that almost certainly means that Nick Evans won’t make the team.  And neither Emaus or Murphy is stellar with the glove, meaning neither guy would be an ideal late-inning defensive replacement – that will probably Hu’s job.Evans, for what it’s worth, is projected to have a higher TAv than either Murph or Emaus -- .269.  In this scenario, the Mets could keep Evans and Murphy and use Hu as a defensive replacement and occasional starter against lefties.  Indeed, Hu hit lefties in triple-A at a  .435/.452/.594 clip.  That scenario’s only problem is that it means Emaus must be offered back to the Jays.   Thus, if Murphy flops at second, the Mets are stuck with Turner as the only player left in the organization capable of playing second on an everyday basis.What’s the ideal solution?  I think it has to be sending Murph down to Triple-A to begin the year.  This would allow him to get more reps at second and allow the Mets to get a real-time evaluation of whether Emaus can be an everyday big leaguer.  The Mets can keep Emaus and Evans for now and make a more informed decision going forward as the season progresses.This would mean Evans is the backup for Ike and Wright.  Hu is the back-up middle infielder and the everyday starting second baseman will be Emaus.  That leaves Willie Harris the only left-handed bat on the bench for some games, although with Beltran and Thole both having regular days off, that problem is mitigated somewhat.Overall, this is a nice problem to have and short of picking Luis at second, a set of choices the Mets really can’t mess up.